Question

sin+sin^2=sec^2-tan^2 find cos^2+cos^4

Answer 1

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$sin + {sin}^{2} = {sec}^{2} - {tan}^{2} \\ = > sin + {sin}^{2} = 1 \\ = > sin = 1 - {sin}^{2} \\ = > sin = {cos}^{2} \\ now \: \: {cos}^{2} + {cos}^{4} \\ = >sin + {sin}^{2} = 1$